ISO/IEC/IEEE 8802-1CM:2019

INTERNATIONAL ISO/IEC/
STANDARD IEEE
8802-1CM
First edition
2019-07
Telecommunications and information
exchange between information
technology systems — Requirements
for local and metropolitan area
networks —
Part 1CM:
Time-sensitive networking for
fronthaul
Télécommunications et échange entre systèmes informatiques —
Exigences pour les réseaux locaux et métropolitains —
Partie 1CM: Réseaux à temps critique pour fronthaul
Reference number
©
IEEE 2018
© IEEE 2018
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ISO/IEC/IEEE 8802‐1CM was prepared by the LAN/MAN of the IEEE Computer Society (as IEEE Std
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© IEEE 2018 – All rights reserved
iii
IEEE Std 802.1CM™-2018
IEEE Standard for
Local and metropolitan area networks—
Time-Sensitive Networking for Fronthaul
Sponsor
LAN/MAN Standards Committee
of the
IEEE Computer Society
Approved 7 May 2018
IEEE-SA Standards Board
Abstract: This standard defines profiles that select features, options, configurations, defaults,
protocols, and procedures of bridges, stations, and LANs that are necessary to build networks that
are capable of transporting fronthaul streams, which are time sensitive.

Keywords: bridged network, fronthaul, IEEE 802 , IEEE 802.1™, IEEE802.1CM™,
synchronization, time-sensitive networking, TSN, Virtual Local Area Network, VLAN, VLAN Bridge
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Participants
At the time of approval of this standard, the IEEE 802.1 Working Group had the following membership:
Glenn Parsons, Chair
John Messenger, Vice Chair
János Farkas, Chair, Time-Sensitive Networking Task Group, Editor
Ralf Assmann Marina Gutiérrez Karen Randall
Shenghua Bao Stephen Haddock
Maximilian Riegel
Gordon Bechtel Mark Hantel Jessy V. Rouyer
Jens Bierschenk Marc Holness Soheil Samii
Steinar Bjørnstad Lokesh Kabra Atsushi Sato
Christian Boiger Michael Karl Frank Schewe
Paul Bottorff Stephan Kehrer Michael Seaman
Radhakrishna Canchi Hajime Koto Johannes Specht
David Chen
Yizhou Li Patricia Thaler
Feng Chen Christophe Mangin Paul Unbehagen
Weiying Cheng Scott Mansfield Hao Wang
Paul Congdon James McIntosh Tongtong Wang
Rodney Cummings Robert Moskowitz Xinyuan Wang
Hesham ElBakoury Tero Mustala Karl Weber
Norman Finn Tomoki Ohsawa Brian Weis
Mickaël Fontaine
Donald R. Pannell Jordon Woods
Geoffrey Garner Takahiro Yamaura
Walter Pienciak
Eric W. Gray Michael Potts Xiang Yu
Craig Gunther Wei Qiu Nader Zein
The following members of the individual balloting committee voted on this standard. Balloters may have
voted for approval, disapproval, or abstention.
Thomas Alexander Stephen Haddock Glenn Parsons
Butch Anton Marco Hernandez Bansi Patel
Werner Hoelzl
Stefan Aust Clinton Powell
Gordon Bechtel Noriyuki Ikeuchi Alon Regev
Harry Bims Atsushi Ito Maximilian Riegel
Steinar Bjørnstad Raj Jain Robert Robinson
Christian Boiger SangKwon Jeong Jessy V. Rouyer
Piotr Karocki
Demetrio Bucaneg, Jr. Peter Saunderson
William Byrd Stuart Kerry Michael Seaman
Juan Carreon Yongbum Kim Thomas Starai
Keith Chow Mark Laubach Walter Struppler
Todor Cooklev Han Hyub Lee Bo Sun
Rodney Cummings Hyeong Ho Lee Richard Tse
Lars Ellegaard John Lemon Mark-Rene Uchida
Marc Emmelmann Michael Lynch Dmitri Varsanofiev
Yonggang Fang Elvis Maculuba Kari Vierimaa
János Farkas Richard Maiden George Vlantis
Norman Finn Khurram Waheed
Roger Marks
Avraham Freedman John Messenger Lisa Ward
Matthias Fritsche Michael Montemurro Hung-Yu Wei
Yukihiro Fujimoto Nick S. A. Nikjoo Andreas Wolf
Devon Gayle Satoshi Obara Oren Yuen
Eric W. Gray Nader Zein
Robert O’Hara
Randall Groves Zhen Zhou
When the IEEE-SA Standards Board approved this standard on 7 May 2018, it had the following
membership:
Jean-Philippe Faure, Chair
Gary Hoffman, Vice Chair
John D. Kulick, Past Chair
Konstantinos Karachalios, Secretary
Chuck Adams Thomas Koshy Robby Robson
Masayuki Ariyoshi Joseph L. Koepfinger* Dorothy Stanley
Adrian Stephens
Ted Burse Kevin Lu
Mehmet Ulema
Stephen Dukes Daleep Mohla
Phil Wennblom
Doug Edwards Damir Novosel
Ronald C. Petersen Howard Wolfman
J. Travis Griffith
Annette D. Reilly Yu Yuan
Michael Janezic
*Member Emeritus
Introduction
This introduction is not part of IEEE Std 802.1CM-2018, IEEE Standard for Local and metropolitan area networks—
Time-Sensitive Networking for Fronthaul.
This standard defines profiles that select features, options, configurations, defaults, protocols and procedures
of bridges, stations, and LANs that are necessary to build networks that are capable of transporting fronthaul
streams, which are time-sensitive.
Contents
1. Overview . 10
1.1 Scope. 10
1.2 Purpose. 10
1.3 Introduction. 10
2. Normative references . 12
3. Definitions . 13
4. Acronyms and abbreviations . 14
5. Conformance . 16
5.1 Requirements terminology. 16
5.2 Profile Conformance Statement (PCS) . 16
5.3 Bridge requirements. 16
5.4 Bridge options. 17
5.5 End station requirements . 18
5.6 End station options. 18
6. Fronthaul . 20
6.1 Evolved Universal Terrestrial Radio Access background . 21
6.2 Class 1 requirements. 21
6.3 Class 2 requirements. 23
6.4 Synchronization requirements . 26
7. Bridge and synchronization functions . 31
7.1 Latency components . 31
7.2 Bridge delay calculation . 31
7.3 Frame preemption . 33
7.4 Network synchronization. 33
7.5 Flow control. 37
7.6 Energy Efficient Ethernet . 37
8. Fronthaul profiles . 39
8.1 Profile A. 40
8.2 Profile B. 42
9. Synchronization solutions . 44
9.1 Solution for Category A+ . 44
9.2 Solutions for Category A . 44
9.3 Solutions for Category B . 44
9.4 Solutions for Category C . 44
Annex A (normative) PCS proforma—Time-Sensitive Networking for Fronthaul Profiles. 45
Annex B (informative) Delay calculation examples. 55
Annex C (informative) Bibliography. 59
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
IEEE Standard for
Local and metropolitan area networks—
Time-Sensitive Networking for Fronthaul
1. Overview
1.1 Scope
This standard defines profiles that select features, options, configurations, defaults, protocols and procedures
of bridges, stations, and LANs that are necessary to build networks that are capable of transporting fronthaul
streams, which are time-sensitive.
NOTE—Stream and flow are used as synonyms in this document.
1.2 Purpose
The purpose of this standard is to specify defaults and profiles that enable the transport of time-sensitive
fronthaul streams in Ethernet bridged networks.
1.3 Introduction
Fronthaul provides connectivity between functional blocks of a cellular base station (BS). The fronthaul
flows between these functional blocks have stringent quality of service requirements. The successful support
of fronthaul flows in a bridged network requires the selection of specific features and options that are

specified in a number of different standards, some developed by IEEE Project 802 , and others (in
particular, those that relate to functionality in OSI layer 3 and above; ISO/IEC 7498:1994 [B11]) developed
by other standards organizations.
This standard selects features and options that support OSI layers 1 and 2 in bridges and end stations from
the following specifications:
— Virtual Local Area Network (VLAN) Bridge specification in IEEE Std 802.1Q.
— MAC service specifications in IEEE Std 802.1AC.
Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this
standard.
The numbers in brackets correspond to those of the bibliography in Annex C
Information on references can be found in Clause 2.
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
— MAC/PHY technology specifications in IEEE Std 802.3.
— Interspersing express traffic specification in IEEE Std 802.3br.
— Frame preemption specification in IEEE Std 802.1Q.
— Time synchronization and Precision Time Protocol (PTP) specifications in IEEE Std 1588.
— Telecom profile specification in ITU-T G.8275.1, which is based on IEEE Std 1588.
— Synchronous Ethernet specification in ITU-T G.8261, G.8262, and G.8264.
To specify and explain the selection of features and options, this standard:
a) Describes fronthaul requirements (Clause 6), specifying two classes of requirements (6.2, 6.3) that
depend on the BS functional decomposition, and specifying synchronization requirements (6.4) that
apply to both classes.
b) Describes how the operation of bridges and bridged networks affects the quality of service provided
by the fronthaul bridged network (Clause 7), providing details to assist in the calculation of latency
(7.1, 7.2, 7.3), the selection of network synchronization methods (7.4), and the potential impact of
the use of flow control (7.5) and Energy Efficient Ethernet (EEE, 7.6).
c) Specifies two bridge profiles (Clause 8) that support the construction of bridged networks meeting
fronthaul requirements. Profile A (8.1) is applicable to bridges that do not support frame preemption
(7.3), while Profile B (8.2) involves frame preemption to accommodate larger non-fronthaul flows
and frame sizes while preserving fronthaul traffic guarantees.
d) Discusses the applicability (Clause 9) of the synchronization methods described in 7.4 to the time
synchronization categories defined in 6.4.1.
e) Defines fronthaul profile conformance requirements (Clause 5) for bridges meeting either Profile A
or Profile B requirements, for end stations and for synchronization.
f) Provides a Profile Conformance Statement (PCS, Annex A) to support clear detailed statements of
equipment conformance to fronthaul profile requirements.
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
2. Normative references
The following referenced documents are indispensable for the application of this document (i.e., they must
be understood and used, so each referenced document is cited in the text and its relationship to this
document is explained). For dated references, only the edition cited applies. For undated references, the
latest edition of the referenced document (including any amendments or corrigenda) applies.
 4, 5
IEEE Std 802 , IEEE Standard for Local and Metropolitan Area Networks—Overview and Architecture.
IEEE Std 802.1AC, IEEE Standard for Local and Metropolitan Area Networks—Media Access Control
(MAC) Service Definition.
IEEE Std 802.1Q, IEEE Standard for Local and Metropolitan Area Networks—Bridges and Bridged
Networks.
IEEE Std 802.3, IEEE Standard for Ethernet.
IEEE Std 802.3br, IEEE Standard for Ethernet—Amendment 5: Specification and Management
Parameters for Interspersing Express Traffic.
IEEE Std 1588, IEEE Standard for a Precision Clock Synchronization Protocol for Networked
Measurement and Control Systems.
ITU-T G.8261, Timing and synchronization aspects in packet networks.
ITU-T G.8262, Timing characteristics of a synchronous Ethernet equipment slave clock.
ITU-T G.8264, Distribution of timing information through packet networks.
ITU-T G.8271.1, Network limits for time synchronization in packet networks.
ITU-T G.8272, Timing characteristics of primary reference time clocks.
ITU-T G.8272.1, Timing characteristics of enhanced primary reference time clocks.
ITU-T G.8273.2, Timing characteristics of telecom boundary clocks and telecom time slave clocks.
ITU-T G.8273.3, Timing characteristics of telecom transparent clocks.
ITU-T G.8275.1, Precision time protocol telecom profile for phase/time synchronization with full timing
support from the network.
MEF 10.3, Ethernet Services Attributes Phase 3.
IEEE publications are available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org/).
The IEEE standards or products referred to in this clause are trademarks of The Institute of Electrical and Electronics Engineers, Inc.
ITU-T publications are available from the International Telecommunications Union (http://www.itu.int/).
MEF technical specifications are available from the MEF Forum (https://www.mef.net/).
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
3. Definitions
For the purposes of this document, the following terms and definitions apply. The IEEE Standards
Dictionary Online should be consulted for terms not defined in this clause.
This standard makes use of the following terms defined in IEEE Std 802:
— bridge
— end station
— Ethernet
—forwarding
—frame
— Local Area Network (LAN)
This standard makes use of the following terms defined in IEEE Std 802.1Q:
— bridged network
— latency
— port
— priority-tagged frame
— traffic class
— untagged frame
— Virtual Local Area Network (VLAN)
— VLAN Bridge
— VLAN-tagged frame
The following terms are specific to this standard:
Category: An identifier of time synchronization requirements.
NOTE—See 6.4.1.
Class: A collective term for fronthaul interfaces that applies a particular functional decomposition of a
cellular base station and a particular treatment of fronthaul information flows.
NOTE—See 6.2 and 6.3.
fronthaul: The connectivity between the functional blocks (e.g., baseband processing and radio frequency
blocks) of a cellular base station.
periodic: Repeating continuously, with a constant time (the period) between each occurrence.
Synchronous Ethernet: A method to distribute frequency synchronization over the Ethernet physical layer
according to IEEE Std 802.3 and ITU-T Recommendations G.8261, G.8262, G.8264.
time window: A time interval (among back-to-back time intervals of the same duration), within which
packets of a specified flow can be sent.
IEEE Standards Dictionary Online is available at: http://dictionary.ieee.org.
The Categories used in this standard are defined by the Requirements for the eCPRI Transport Network [B6].
Synchronous Ethernet has been defined to be fully conformant to IEEE Std 802.3, as documented in the relevant ITU-T
Recommendations G.8261, G.8262, G.8264.
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
4. Acronyms and abbreviations
3GPP 3rd Generation Partnership Project
BC boundary clock
BS base station
C&M Control and Management
CBR Constant Bit Rate
CPRI Common Public Radio Interface
CRC Cyclic Redundancy Check
cTE constant Time Error
C-VLAN Customer VLAN
dTE dynamic Time Error
eRE eCPRI Radio Equipment
eREC eCPRI Radio Equipment Control
EEE Energy Efficient Ethernet
EISS Enhanced Internal Sublayer Service
ESMC Ethernet Synchronization Messaging Channel
E-UTRA Evolved Universal Terrestrial Radio Access
FID Filtering Identifier
FLR Frame Loss Ratio
GM Grandmaster
GNSS Global Navigation Satellite System
GPS Global Positioning System
HPF High Priority Fronthaul
IET Interspersing Express Traffic
IPG Inter Packet Gap
IQ In-phase and Quadrature modulation
ISS Internal Sublayer Service
LAN Local Area Network
LPF Low Priority Fronthaul
LPI Low Power Idle
MAC Medium Access Control
eCPRI is a not an acronym; eCPRI is specified by the eCPRI Interface Specification [B5].
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
max|TE| maximum absolute Time Error
max|TE| maximum absolute relative Time Error
relative
MPF Medium Priority Fronthaul
OFDM Orthogonal Frequency Division Multiplexing
PCS Profile Conformance Statement
PDU Protocol Data Unit
PHY physical layer
PICS Protocol Implementation Conformance Statement
PRTC Primary Reference Time Clock
PTP Precision Time Protocol
PVID Port VID
RE Radio Equipment
REC Radio Equipment Control
RSTP Rapid Spanning Tree Protocol
SC Slave Clock
SFD Start Frame Delimiter
SyncE Synchronous Ethernet
TAI Temps Atomique International—International Atomic Time
T-BC Telecom Boundary Clock
TC transparent clock
TE Time Error
TDM Time Division Multiplexing
T-GM Telecom Grandmaster
TSN Time-Sensitive Networking
T-TC Telecom Transparent Clock
T-TSC Telecom Time Slave Clock
UE User Equipment
UNI User Network Interface
VID VLAN Identifier
VLAN Virtual LAN
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
5. Conformance
A claim of conformance to this standard is a claim that the behavior of an implementation of a bridge
(5.3, 5.4) or of an end station (5.5, 5.6) meets the mandatory requirements of this standard and may support
options identified in this standard.
5.1 Requirements terminology
For consistency with existing IEEE and IEEE 802.1 standards, requirements placed upon conformant
implementations of this standard are expressed using the following terminology:
a) Shall is used for mandatory requirements;
b) May is used to describe implementation or administrative choices (“may” means “is permitted to,”
and hence, “may” and “may not” mean precisely the same thing);
c) Should is used for recommended choices (the behaviors described by “should” and “should not” are
both permissible but not equally desirable choices).
The Profile Conformance Statement (PCS) proformas (see Annex A) reflect the occurrences of the words
“shall,” “may,” and “should” within the standard.
The standard avoids needless repetition and apparent duplication of its formal requirements by using is, is
not, are, and are not for definitions and the logical consequences of conformant behavior. Behavior that is
permitted but is neither always required nor directly controlled by an implementer or administrator, or
whose conformance requirement is detailed elsewhere, is described by can. Behavior that never occurs in a
conformant implementation or system of conformant implementations is described by cannot. The word
allow is used as a replacement for the phrase “support the ability for,” and the word capability means “can
be configured to.”
5.2 Profile Conformance Statement (PCS)
The supplier of an implementation that is claimed to conform to this standard shall provide the information
necessary to identify both the supplier and the implementation, and shall complete a copy of the PCS
proforma provided in Annex A.
5.3 Bridge requirements
This subclause defines the conformance requirements for bridge implementations claiming conformance to
this standard. Each bridge implementation supports one or more profiles defined in this standard. Each
profile includes the common bridge requirements (5.3.1). A bridge implementation that conforms to the
provisions of this standard shall support Profile A requirements (5.3.2).
5.3.1 Common bridge requirements
A minimum set of features specified in IEEE Std 802.1Q are required for a bridge to support this standard.
That is, the bridge shall be a VLAN Bridge supporting the minimum set of features identified in this
subclause. The requirements of this subclause do not imply that a VLAN Bridge implementation that
conforms to the provisions of this standard has to support options specified in IEEE Std 802.1Q-2018 other
than those identified in this subclause.
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
A bridge implementation that conforms to the provisions of this standard shall:
a) Conform to the relevant standard for the MAC technology implemented at each port in support of
the MAC Internal Sublayer Service (ISS), as specified in IEEE Std 802.1AC;
b) Implement full duplex IEEE 802.3 MAC with data rate of 1 Gbps or greater on each port;
c) Support the capability of 2000 octets maximum size MAC Protocol Data Unit (PDU) on each port;
d) Support the capability to disable MAC control PAUSE if it is implemented;
e) Support the capability not to assert Low Power Idle (LPI) on each port that supports Energy
Efficient Ethernet (EEE, specified in IEEE Std 802.3);
f) Meet the VLAN Bridge requirements stated in items a) through f) in 5.4 of IEEE Std 802.1Q-2018;
g) Support an active topology enforcement mechanism;
h) Meet the VLAN Bridge requirements stated in items g) and h) in 5.4 of IEEE Std 802.1Q-2018 if the
supported active topology enforcement mechanism is the Rapid Spanning Tree Protocol (RSTP);
i) Meet the VLAN Bridge requirements stated in items i) through n) in 5.4 of IEEE Std 802.1Q-2018;
j) Support at least the Acceptable Frame Types parameter value of Admit All frames on each port [see
item l) in 5.4 of IEEE Std 802.1Q-2018];
k) Support the use of at least one VLAN Identifier (VID);
l) Meet the VLAN Bridge requirements stated in items p) through r) in 5.4 of IEEE Std 802.1Q-2018;
m) Support the ability to allocate the Port VID (PVID) and all other VIDs to the single Filtering
Identifier (FID) if only a single FID is supported [item q) in 5.4 of IEEE Std 802.1Q-2018], i.e.,
support shared VLAN learning (8.8.8 of IEEE Std 802.1Q-2018);
n) Support a minimum of three traffic classes (3.268 of IEEE Std 802.1Q-2018) on all ports;
o) Support the strict priority algorithm for transmission selection (8.6.8.1 of IEEE Std 802.1Q-2018)
on each port for each traffic class;
p) Support flow metering (8.6.5 of IEEE Std 802.1Q-2018) with the token bucket bandwidth profile
specified in MEF 10.3;
q) Support the capability to disable Priority-based flow control if it is implemented (Clause 36 of
IEEE Std 802.1Q-2018).
5.3.2 Bridge requirements for Profile A
A bridge implementation for which a claim of conformance to Profile A (8.1) is made, shall support items a)
through q) of the common bridge requirements (5.3.1).
5.4 Bridge options
A bridge implementation that conforms to the provisions of this standard may:
a) Support MEF 10.3 token sharing for the token bucket bandwidth profile, which is used for flow
metering [item p) in 5.3.1; 8.6.5 of IEEE Std 802.1Q-2018];
b) Support Profile B (5.4.1, 8.2);
c) Support synchronization in the bridged network (5.4.2, Clause 9).
5.4.1 Bridge requirements for Profile B
A bridge implementation for which a claim of conformance to Profile B (8.2) is made, shall:
Support of synchronization in the bridged network is optional if methods [items c) and d) in 7.4] that put no requirements on the
bridged network are available to be used to support synchronization.
IEEE Std 802.1CM-2018
IEEE Standard for Local and metropolitan area networks—Time-Sensitive Networking for Fronthaul
a) Support items a) through q) of the common bridge requirements (5.3.1);
b) Support Frame Preemption, i.e.,
1) Support item ad) in 5.4.1 of IEEE Std 802.1Q-2018 (see also 7.3);
2) Support Interspersing Express Traffic (IEEE Std 802.3br, see also 7.3) ;
3) Support Frame Preemption and Interspersing Express Traffic on each port whose data rate is
not higher than 10Gbps;
4) Support the configuration of 64-octet fragment size for Interspersing Express Traffic at each
port for which Interspersing Express Traffic is enabled.
5.4.2 Bridge requirements for synchronization
A bridge implementation for which a claim of conformance to support synchronization in the bridged
network (Clause 9) is made, shall:
a) Support untagged frames on all ports;
b) Support the ITU-T G.8275.1 telecom profile
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